An “ondol” is an underfloor heating system used in traditional Korean architecture. The system typically included a cooking fire or stove in a kitchen that was surrounded by one or more rooms of the house built on a raised masonry floor two or three feet higher than the kitchen. Extending through the raised masonry floor were horizontal smoke passages that led to a standing chimney providing a draft through the passages. Heat from the fire or stove would travel through the horizontal smoke passages to heat the rooms of the house. The horizontal smoke passages were usually covered by stone slabs, clay or concrete, which formed the heated floor of the rooms, and a water-impervious layer, such as oiled paper, which formed the finished flooring on the heated floor.
It is appreciated that an efficient ondol system required a delicate balance between two conflicting factors. On the one hand, for fuel to burn well in the fire or stove, the passages should provide good air flow from the fire to the chimney. On the other hand, for effective heating of the rooms, hot air should linger in the passages as long as possible to warm the stone slabs, clay or concrete forming the heated floor. To accomplish this, the passages were lengthened for multiple passes under each room, thus preventing the hot air from exiting through the chimney too quickly. When the correct balance was achieved, a room could be kept warm all night by the stone slabs, clay or concrete heated by a fire that lasted only a couple of hours.
Evolution of Korean architecture led to multi-story housing and improved ondol systems. However, flue gases from burning wood or coal caused many deaths from carbon monoxide poisoning. As a result, flue gas systems have given way to electric heating elements and/or piping circulating heated water (or “hydronics”).
In a “poured floor” or “wet floor” system, electric heating elements or hydronic piping extend through a “light” (more porous) concrete floor that is poured above a concrete slab. The wet floor system has many drawbacks, including the 15-20 day curing period for both layers of concrete, the upper layer of which cannot be poured until the lower layer has completely cured. The curing period can also be extended significantly if the concrete is poured during rainy or winter season. In cold climate, the concrete can even freeze.
After curing, the concrete can absorb water which can significantly increase its weight and evaporate during warmer weather causing the finishing flooring or laminate to buckle and warp. Moreover, in high-rise buildings and multi-story residential buildings, concrete can create poor acoustics as sound and impact waves can travel through concrete between floors and echo throughout the building. In that regard, while impact and/or sound may involve different physical events with different physical effects, impact and/or sound deadening are used interchangeably and collectively herein as “impact and/or sound deadening” or “ISD.”
Laying a sub-floor and piping in a “poured floor” or “wet floor” system is labor and time intensive. Different stages of construction and installation of a poured or wet floor system require time, scheduling and a team of professional workers with an array of different skills and experience. If any part of the subfloor, piping or heating element in a “poured floor” or “wet floor” system is subsequently damaged, the concrete subfloor of the entire room or area must be cracked and removed in order to access and replace the damaged piping or heating element. The concrete subfloor must then be repoured over the replacement piping or heating element.
Accordingly, there is a need for a heating and/or cooling sub-flooring system which advantageously uses hydronics or hydronic principles for thermal conduction while minimizing or avoiding entirely the use of concrete. It is desirable that such sub-flooring system be easy to install, in terms of labor, time and the skills required of workers whether or not they are trained professionals. It is further desirable that such sub-flooring system include environmentally-friendly components and that such sub-flooring system be adapted for use in multi-dwelling highrise buildings and multi-story residential buildings with significantly improved impact and/or sound deadening.